Hi Tyler, Jim makes very good points. If money is not an issue, then you'd also need to consider your time, which at this point would be an unknown since it's not currently running. If you can get it started, then you can make an assessment of whether "everything" works. If through some stroke of luck, everything does work satisfactorily, then as Jim pointed out, you're probably up for a few thousand to replace the undercarriage - that's where most of the value of these machines sit. Replacing undercarriage though is a "guaranteed" fix since it would all be new and there's no realistic chance of a failure. You might also be able to use it as-is, if the tracks can be adjusted so they don't fall off as you turn with a load in the bucket. You'd need to weigh all of that against the immediate utility you'd get from a skidsteer or even small loader in good condition but also the price you'd have to pay for one of those.
So offer him scrap price, then get it going and come back here with your findings on how well it runs - don't worry about the undercarriage because we can already see that it's spent